Very small flakes are added to materials in a fluid state, including paints, to give them unique properties. Automotive paints have very small flakes suspended in the paint to produce a glitter-type appearance. Such flakes are also useful in tailoring the spectral reflectance of paints, particularly in the visible and infrared wavelength spectrum. They have been found to be useful in improving the properties of radar absorbing materials including paints and bulk materials used to reduce the radar signature of aircraft. Unfortunately, the glitter-type appearance may be reduced by a rough surface texture of the flakes.
Prior art methods of producing very small flakes use a ball mill wherein ball bearings are used to smash metal particles. When using a ball mill, spherical particles are placed inside a container along with ball bearings. The container is then vibrated. A disadvantage of using a ball mill is that a ball mill produces random impacts on the material particles and produces flakes of random geometry and size. Flakes produced by a ball mill have irregular edges and surfaces that are roughened by pressure bonded inclusions. The ball mill process is very inefficient and may break larger flakes before they can be removed. Additionally, flakes from a ball mill process are not uniformly flat and often stick together.